Preparation of (±) 4-demethoxy-6 (and-11-)-deoxydaunomycinone

ABSTRACT

(±)4-demethoxy-6(and-11-)-deoxydaunomycinone which are starting materials for anthracycline antitumor antibiotics are prepared by reacting 1,2,3,6-tetrahydrophthalic anhydride with an alcohol of the formula ROH, wherein R is lower alkyl, substituted lower alkyl or aryl to form a monoester, subjecting the monoester to a Friedel-Crafts reaction with acetyl chloride, followed by mild alkaline treatment, to give the corresponding α,β unsaturated ketone, catalytically reducing same to form the corresponding 4-acetyl-perhydrophthalate reacting the latter with 1,4-dimethoxynaphthalone in the presence of tritluoroacetic anhydride and trifluoroacetic acid to form a mixture of two isomeric compounds, submitting said mixture of isomers to a catalytic reduction of the benzylic carbonyl function, followed by treatment thereof with sulphuric acid at room temperature to afford a mixture of tetracyclic isomers, treating the mixture of tetracyclic isomers with sulphuric acid at 80° C. for one hour to give a 1:1 mixture of the racemic anthracyclinones above mentioned.

This is a division of application Ser. No. 382,144 filed May 26, 1982now U.S. Pat. No. 4,465,671.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a new class of anthracycline glycosideshaving antitumor activity, methods for their preparation, pharmaceuticalcompositions containing them and the use thereof in treating certainmammalian tumors. The invention also relates to the aglycones of thenovel glycosides and certain novel intermediates.

2. Prior Art

The new anthracyclines of the invention are related to the knownantitumor glycosides daunorubicin and doxorubicin, both of which areamply described in the literature and both of which are at present beingclinically used in treating certain tumors.

SUMMARY OF THE INVENTION

The invention provides, in one aspect thereof, a new class ofanthracycline glycosides of the formula (I): ##STR1## wherein one of R₁and R₂ is hydrogen and the other of R₁ and R₂ is hydroxy, each of R₃, R₄and R₅ is independently selected from the group consisting of hydrogenand hydroxy and X is hydrogen or trifluoroacetyl, with the provisos thatR₄ and R₅ are not simultaneously hydroxy and that if R₃ is hydroxy, thenX is hydrogen.

The new anthracycline glycoside antibiotics of the invention, i.e.,those of formula (I), are condensation products of (a) a noveltetracyclic aglycone, i.e., anthracyclinones having ahydroxy-anthraquinone chromophoric system of the formula II ##STR2##wherein R₁ and R₂ are as defined above and (b) a protected halosugar ofthe formula III ##STR3## wherein Y is a halogen, preferably chlorine,and each of R₆ and R₇ is independently selected from the groupconsisting of hydrogen and trifluoroacetoxy, with the proviso that R₆and R₇ are not simultaneously trifluoroacetoxy.

Accordingly, in another aspect thereof the invention provides the newclass of aglycones of the formula (II).

The reaction scheme for the preparation of the anthracyclinones (II) isset forth below: ##STR4##

The actual starting materials for the reaction sequences are1,2,3,6-tetrahydrophthalic anhydride (1) and 1,4-dimethoxynaphthalene(5). Compound (1) is treated with an alcohol of the formula ROH, whereinR is alkyl, substituted alkyl or aryl group, to yield the correspondingmonoester (2), which is then subjected to a Friedel-Crafts reaction withacetyl chloride followed by mild alkaline treatment to give thecorresponding α,β-unsaturated ketone (3). The acylation reaction is aregiospecific process giving only the C-4 acetyl derivative. Thecatalytic reduction of (3) quantitatively affords the acid (4) which isa key intermediate in the synthesis of the tetracyclic chromophore. Theacid (4) is promptly converted to (6) (mixture of two isomers) byreaction with 1,4-dimethoxy-naphthalene (5) in the presence oftrifluoroacetic anhydride and trifluoroacetic acid. The catalyticreduction of the benzylic carbonyl function of (6), followed bytreatment with sulphuric acid at room temperature affords the mixture oftetracyclic isomers (7). Treatment of (7) with sulphuric acid at 80° C.gives a mixture of the new athracyclinones (8) and (9). The introductionof hydroxyl groups to give (10) and (11) is carried out by conventionalmethods, which have already been described. In fact the proceduresfollowed for the oxidation of the ketones (8) and (9) to thecorresponding hydroxyketones (10) and (11) are those employed withrespresentative 20-ketosteroids [i; KOt.Bu/O₂, DMF,-20° C.; ii; (EtO)₃P, DMF,-20° C.; J. N. Garden et al, J. Org. Chem., 33,3294, (1968)]; ori; [Ac₂ O, HClO₄ ; ii; m-chloroperbenzoic acid; J. Attenburrow et al, J.Chem. Soc., 4547, (1961)].

Finally, the introduction of the 7-hydroxyl groups in compounds (10) and(11) is accomplished by benzylic bromination followed by solvolysis [C.M. Wong et al, Can. J. Chem., 51, 446 (1973)]. The optical resolution iscarried out by the conventional method of conversion todiastereoisomeric derivatives using a chiral resolving agent (C. T.Eliel, "Stereochemistry of Carbon Compounds", McGraw Hill, 1962 Chapter4) and affords (+) 4-demethoxy-6-deoxydaunomycinone (II; R₁ ═OH, R₂ ═H)and (+) 4-demethoxy-11-deoxydaunomycinone (II; R₁ ═H, R₂ ═OH).

The racemic anthracyclinones II may be condensed with the protectedhalo-sugars 1-chloro-N,O-ditrifluoroacetyldaunosamine (III; Y═Cl, R₆═CF₃ COO, R₇ ═H), 1-chloro-N,O-ditrifluoroacetyl-4-epi-daunosamine (III;Y═Cl, R₆ ═H, R₇ ═CF₃ COO) and1-chloro-N-trifluoroacetyl-4-deoxy-daunosamine (III; Y═Cl, R₆ ═R₇ ═H) inthe presence of silver trifluoromethane-sulphonate to give an easilyseparated mixture of protected anthracycline α-glycosides 7S:9S and7R:9R, following the method described in U.S. Pat. No. 4,107,423 ownedby the assignee hereof.

Removal of the O-trifluoroacetyl group, if present, by treatment withmethanol leads to the anthracycline glycosides I (X═COCF₃, R₃ ═H). Mildalkaline hydrolysis removes the N-trifluoroacetyl group to give thedaunorubicin derivatives I (X═R₃ ═H), which may be converted to thecorresponding doxorubicin derivatives I(X═H, R₃ ═OH) by 14-brominationand treatment with sodium formate in accordance with the methoddescribed in U.S. Pat. No. 3,803,124, owned by the unrecorded assigneehereof.

The processes described hereinabove are within the scope of theinvention, and accordingly, in another aspect thereof the inventionprovides such processes.

As is apparent from the foregoing, these processes involve thepreparation and use of several novel intermediates. These too are withinthe scope of the present invention.

In yet another aspect thereof, the invention provides pharmaceuticalcompositions comprising an anthracycline glycoside according to theinvention in admixture with a pharmaceutically acceptable diluent orcarrier therefor.

Finally, the invention provides methods of treating certain mammaliantumors using the new anthracycline glycosides of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in greater detail in the followingpreparative examples.

EXAMPLE I Preparation of monomethyl 1,2,3,6-tetrahydrophthalate[(2)R═CH₃ ]

A solution of 50 g (0.329 mol of 1,2,3,6-tetrahydrophthalic anhydride(1) in a mixture of 200 ml of methylene dichloride and 300 ml ofmethanol containing 1 g of p toluenesulphonic acid was refluxed for 4hours. The solvents were then evaporated off under reduced pressure, andthe residue was dissolved in chloroform, washed with water andevaporated to dryness to give 56 g of the title compound (yield 83%),which was recrystallized from petroleum ether (60°); m.p. 85° C.TLC onkieselgel plates Merck F₂₅₄ (chloroform:acetone, 2:1 by volume): Rf 0.28

EXAMPLE II Preparation of monomethyl4-acetyl-1,2,3,6-tetrahydrophthalate [(3)R═CH₃ ]

To a suspension of 85 g (0.64 mol) of anhydrous aluminum trichloride in1.5 liters of anhydrous methlene dichloride under stirring, in anitrogen atmosphere 75 ml (1 mol) of acetyl chloride were added dropwiseat -5° C. Consecutively, 40 g (0.217 mol) of the compound prepared inExample I in 750 ml of anhydrous methylene dichloride were added over aperiod of 2 hours. The reaction mixture was kept at -5° C. for 6 hoursand then at room temperature overnight. After the addition of 1 kg ofice, the organic phase was separated off, washed with water, andevaporated to a residue. The residue, dissolved in 500 ml of methanol,was treated with 50 g of potassium carbonate at room temperature for 5hours. After filtration, the solvent was evaporated off and the residuewas dissolved in water and washed with chloroform. The aqueous alkalinesolution was adjusted to pH 3 and extracted repeatedly with chloroform.The residue obtained by evaporating off the solvent was purified bychromatography on a column of silicic acid using the solvent systemchloroform:acetone (95:5 by volume). 28 g (57% overall yield) of thetitle compound were obtained and recrystallized from diethylether:petroleum ether, m.p. 94°-96° C. TLC on kieselgel plates MerckF₂₅₄ (chloroform:acetone 2:1 by volume): Rf 0.22

    ______________________________________                                        IR (KBr): 1660 cm.sup.-1                                                                          C═O of α, β-unsaturated ketone                       1690 cm.sup.-1                                                                          C═O of acid                                                     1720 cm.sup.-1                                                                          C═O of ester                                          PMR (CDCl.sub.3):                                                                       2.33 S δ                                                                           ##STR5##                                                           2.55-2.95                                                                                ##STR6##                                                           3.00-3.30                                                                                ##STR7##                                                           3.70                                                                                     ##STR8##                                                           6.91      (m, 1H, C .sub.--H═)                                            9.81      (s, 1H, COO .sub.--H)                                     EI-MS:    m/e 226 (M.sup.+)                                                             m/e 208 (M.sup.+ --H.sub.2 O)                                                 m/e 195 (M.sup.+ --OCH.sub.3)                                                 m/e 180 (M.sup.+ --H.sub.2 O--CO)                                             m/e 121 (M.sup.+ --H.sub.2 O--CO--COOCH.sub.3)                      ______________________________________                                    

EXAMPLE III Preparation of monomethyl 4-acetyl-perhydrophthalate [(4)R═CH₃ ].

A solution of 4.6 g of the compound prepared in Example II in 120 ml ofethanol was hydrogenated at room temperature and 1 atm. in the presenceof 0.6 g of 10% palladium-on-charcoal as catalyst. Evaporation of thesolvent afforded the title compound in quantitative yield.

    ______________________________________                                        IR spectrum (film):                                                                           1680 cm.sup.-1                                                                          CO of acid                                                          1710 cm.sup.-1                                                                          CO of ketone                                                        1730 cm.sup.-1                                                                          CO of ester                                         PMR (CDCl.sub.3):                                                                             1.5-2.6 δ                                                                         (m, 8H)                                                             2.18                                                                                     ##STR9##                                                           3.28      (m, 1H)                                                             3.70                                                                                     ##STR10##                                                          8.53      (bs, 1H, COOH)                                      ______________________________________                                    

EXAMPLE IV Preparation of1,4-dimethoxy-3-(2'-methoxycarbonyl-4'-acetyl-cyclohexylcarbonyl)-naphthaleneand1,4-dimethoxy-3-(2'-methoxycarbonyl-5'-acetyl-cyclohexylcarbonyl)-naphthalene[(6) R═CH₃ ].

A solution of 3.2 g; 0.017 mol of 1,4-dimethoxynaphthalene and 4.0 g;0.017 mol of the compound prepared in Example III in 50 ml oftrifluoroacetic anhydride and 25 ml of trifluoroacetic acid was refluxedfor 24 hours. The residue, obtained by evaporating off the solventsunder reduced pressure, was dissolved in chloroform and washed with anaqueous saturated solution of sodium bicarbonate and then with water.The residue, obtained by evaporation of the solvent, was purified on acolumn of silica gel, using chloroform as the eluting solvent, to give3.5 g of a mixture of the isomeric title compounds. TLC kieselgel platesMerck F₂₅₄ (chloroform:acetone 98:2 by volume). Rf 0.3

FD-MS: m/e 398 (M⁺)

    ______________________________________                                        IR (film): 1660 cm.sup.-1                                                                          CO of α, β-unsaturated ketone                            1710 cm.sup.-1                                                                          CO of ketone                                                        1720 cm.sup.-1                                                                          CO of ester                                              PMR (CDCl.sub.3):                                                                        1.5-2.3 δ                                                                         (m, 8H)                                                             2.18                                                                                     ##STR11##                                                          3.67                                                                                     ##STR12##                                                          3.65      (m, 1H)                                                             4.00-4.02                                                                                ##STR13##                                                          7.01      (s, 1H)                                                             7.5-8.5   (m, 4H)                                                  ______________________________________                                    

EXAMPLE V Preparation of6,6α,7,8,9,10,10α,11-octahydro-5,12-dimethoxy-11-oxo-8-acetyl-naphthaceneand6,6α,7,8,9,10,10α,11-octahydro-5,12-dimethoxy-11-oxo-9-acetyl-naphthacene(7).

A solution of 0.45 g; 1.1 mmol of the mixture of isometric compoundsprepared in Example IV in 40 ml of ethanol and 0.2 ml of concentratedhydrochloric acid was hydrogenated at room temperature in the presenceof 0.3 g of 5% palladium-on-charcoal as catalyst. The catalyst wasfiltered off and the solution was evaporated to a residue under reducedpressure. The residue was dissolved in 10 ml of concentrated sulphuricacid. After standing for 20 minutes the reaction mixture was poured intocold water, and then extracted with chloroform. The organic phase,washed with an aqueous saturated solution of sodium bicarbonate and thenwith water, was evaporated to a residue which was purified bychromatography on a column of silica gel, eluting with chloroform, togive 0.2 g of a mixture of the isomeric title compounds. TLC onkieselgel plates Merck F₂₅₄ (chloroform:acetone 98:2 by volume) Rf 0.33

    ______________________________________                                        EI-MS:    m/e 352 (M.sup.+)                                                             m/e 337 (M--CH.sub.3)                                                         m/e 43 (CH.sub.3 CO.sup.+)                                          IR (KBr): 1680 cm.sup.-1                                                                          C═O of α, β-unsaturated ketone                       1705 cm.sup.-1                                                                          C═O of ketone                                         PMR (CDCl.sub.3):                                                                       1.8-2.8 δ                                                                         (m, 8H)                                                             2.28                                                                                     ##STR14##                                                          3.2-3.8   (m, 3H)                                                             3.95                                                                                     ##STR15##                                                          4.05                                                                                     ##STR16##                                                          7.4-8.4   (m, 4H)                                                   ______________________________________                                    

EXAMPLE VI Preparation of5,7,8,9,10,12-hexahydro-5,12-dioxo-11-hydroxy-9-acetyl-naphthacene (8)and 5,7,8,9,10,12-hexahydro-5,12-dioxo-6-hydroxy-9-acetyl-naphthacene(9)

A solution of 0.05 g of the mixture of isomeric compounds prepared inExample V in 5 ml of concentrated sulphuric acid was heated at 80° C.for one hour. The reaction mixture was poured into cold water andextracted with cloroform. The organic phase, washed with an aqueoussaturated solution of sodium bicarbonate and then with water, wasconcentrated to a small volume under reduced pressure andchromatographed on a column of silica gel, eluting with chloroform, togive a (1:1) mixture of the isomeric title compounds. TLC on silica gelplates Merck F₂₅₄ (chloroform:acetone 98:2 by volume): Rf 0.5

    ______________________________________                                        EI-MS: m/e: 320 (M.sup.+)                                                                 227 (M.sup.+ --CH.sub.3 CO)                                                   259 (M.sup.+ --CH.sub.3 CO--H.sub.2 O)                                        43 (CH.sub.3 CO.sup.+)                                            IR (KBr):   1625 cm.sup.-1                                                                          bonded C═O quinone                                              1670 cm.sup.-1                                                                          free C═O quinone                                                1710 cm.sup.-1                                                                          C═O ketone                                                      2940 cm.sup.-1                                                                          bonded OH                                               PMR (CDCl.sub.3):                                                                         1.8-2.3 δ                                                                         (m, 3H)                                                             2.30                                                                                     ##STR17##                                                          2.6-3.1   (m, 4H)                                                             7.4-8.4   (m, 5H)                                                             11.71 and 11.75 (two s, 1H, OH phenolic)                          UV-Vis (CHCl.sub.3):                                                                      250, 267; 414 nm                                                  ______________________________________                                    

EXAMPLE VII Preparation of 4-demethoxy-6,7-dideoxydaunomycinone (10) and4-demethoxy-7,11-dideoxydaunomycinone (11).

A mixture of (0.32 g) of compounds (8) and (9) prepared as described inExample VI, was dissolved in 38 ml of acetic anhydride and refluxed for18 hours in the presence of 0.19 g of p-toluene-sulphonic acid. Theresidue, obtained by evaporation under reduced pressure of the reactionmixture, was dissolved in 40 ml of methylene dichloride and treated with0.258 g of m-chlorperbenzoic acid. After 2 hours at room temperature thereaction mixture was washed with a saturated aqueous solution of sodiumbicarbonate and then with water. The residue, obtained by evaporation ofthe solvent, was dissolved in a mixture of acetone and ethanol andtreated with 30 ml of 1 N sodium hydroxide for 1 hour at roomtemperature. After conventional processing, the crude product waschromatographed on a column of silica gel, using chloroform as theeluting agent, to afford the title compounds in pure form. Compound (10)TLC on kieselgel plates Merck F₂₅₄ (chloroform:acetone 98:2 by volume):Rf 0.18

    ______________________________________                                        EI-MS: m/e     336 (M.sup.+)                                                                 318 (M--H.sub.2 O)                                                            293 (M--CH.sub.3 CO)                                                          275 (M--CH.sub.3 CO--H.sub.2 O)                                PMR-80 MHz (CDCl.sub.3):                                                                     1.95 δ                                                                            (m, 2H,  .sub.--H-8)                                                2.38                                                                                     ##STR18##                                                          3.01      (m, 4H,  .sub.--H-7,  .sub.--H-10)                                  3.83      (s, 1H, OH-9)                                                       7.64      (s, 1H,  .sub.--H-6)                                                7.70-8.3  (m, 4H, arom)                                                       13.03     (s, 1H, OH-11)                                       IR (KBr):      1620 cm.sup.-1                                                                          bonded C═O quinone                                              1665 cm.sup.-1                                                                          free C═O quinone                                                1705 cm.sup.-1                                                                          C═O ketone                                       UV-Vis (CHCl.sub.3):                                                                         250, 267, 414 nm                                               ______________________________________                                    

Compound (11) TLC on kieselgel plates Merck F₂₅₄ (chloroform:acetone98:2 by volume): Rf 0.15

EI-MS: m/e 336 (M⁺)

    ______________________________________                                        PMR-80 MHz  2.0 δ                                                                             (m, 2H,  .sub.--H-8)                                    (CDCl.sub.3):                                                                             2.38                                                                                     ##STR19##                                                          2.75-3.28 (two d, J = 17.4 Hz, 2H,  .sub.-H-10)                               3.0       (m, 2H,  .sub.--H-7)                                                3.75                                                                                     ##STR20##                                                          7.51      (s, 1H,  .sub.--H-11)                                               7.7-8.4   (m, 4H, arom)                                                       12.99                                                                                    ##STR21##                                              UV-Vis (CHCl.sub.3):                                                                      250, 267, 414 nm                                                  IR (KBr):   1625 cm.sup.-1                                                                          bonded C═O quinone                                              1665 cm.sup.-1                                                                          free C═O quinone                                                1705 cm.sup.-1                                                                          C═O ketone                                          ______________________________________                                    

EXAMPLE VIII Preparation of (±)4-demethoxy-6-deoxydaunomycinone (II: R₁═OH, R₂ ═H)

A solution of 0.5 g of (±)4-demethoxy-6,7-dideoxydaunomycinone (10),prepared as described in Example VII, in 50 ml of benzene was treated atreflux temperature for 4 hours with 1.2 ml of ethylene glycol in thepresence of 0.045 g of p-toluenesulphonic acid, to form thecorresponding 13-ketal derivative (0.4 g) which crystallized directlyfrom the cooled reaction mixture. This ketal compound was dissolved in250 ml of carbon tetrachloride and treated with 2 ml of a solution of3.2 g of bromine in 32 ml of carbon tetrachloride at 45° C. for 6 hoursin the presence of 0.46 g of 2,2'-azo-bis-isobutyronitrile. The cooledreaction mixture was extracted with 1 N aqueous sodium hydroxide and thecolored aqueous phase was adjusted to pH 8.5 and extracted withchloroform. The chloroform extracts, after being evaporated to a smallvolume, afforded 0.11 g of crystalline 4-demethoxy-6-deoxy-13-ketaldaunomycinone.

TLC on kieselgel plates (Merck F₂₅₄) solvent system CHCl₃ --(CH₃)₂ CO(9:1 v/v): Rf 0.21

EI-MS m/e 396 (M⁺)

    ______________________________________                                        PMR (CDCl.sub.3):                                                                       1.47 δ                                                                             ##STR22##                                                          1.53                                                                                     ##STR23##                                                          2.27                                                                                     ##STR24##                                                          3.02                                                                                     ##STR25##                                                          3.90      (d, 1H, OH-7) J = 10.5 Hz                                           4.09                                                                                     ##STR26##                                                          4.90                                                                                     ##STR27##                                                          7.85, 8.26                                                                              (m, 4H, aromatic)                                                   7.98                                                                                     ##STR28##                                                          13.11                                                                                    ##STR29##                                                IR (KBr): 1620 cm.sup.-1                                                                          bonded C═O quinone                                              1670 cm.sup.-1                                                                          free C═O quinone                                      ______________________________________                                    

Finally the hydrolysis of the ketal group was performed by treatmentwith an aqueous solution of hydrogen chloride in acetone (300 ml of a0.25 N solution) at room temperature for 3 hours).

Compound II (R₁ ═OH, R₂ ═H): TLC on kieselgel plates (Merck F₂₅₄) usingsolvent system chloroform:acetone (9:1 by volume): Rf 0.24

FD-MS: m/z 352 (M⁺)

    ______________________________________                                        PMR 270 MHz  2.42                                                                                  ##STR30##                                                (CDCl.sub.3):                                                                              2.98   (d, 1H, H.sub.ax -10, J.sub.gem 17.9 Hz)                               3.13   (d, 1H, H.sub.e -10, J.sub.gem 17.9 Hz)                                4.07   (d, OH-7, J = 10 Hz)                                                   4.46   (s, OH-9)                                                              4.93   (m, H.sub.eq -7, J = 10 Hz after D.sub.2 O                                    addition W.sub.H = 8 Hz)                                               7.99   (s, H-6)                                                               13.07  (s, OH-11)                                                ______________________________________                                    

EXAMPLE IX Preparation of (±)4-demethoxy-11-deoxydaunomycinone (II: R₁═H, R₂ ═OH)

Compound (11), prepared as described in Example VII, is converted to thetitle compound following the procedure described in Example VIII.Compound II (R₁ ═H, R₂ ═OH): TLC on silica gel plates (Merck F₂₅₄)solvent system chloroform:acetone (9:1 by volume): Rf 0.34

    ______________________________________                                        PMR 60 Mz (CDCl.sub.3 /                                                                       2.42 (s, CH.sub.3 CO)                                         DMSO--d.sub.6): 3.08 (d, H.sub.ax -10, J.sub.gem 18 Hz)                                       3.28 (d, H.sub.eq -10, J.sub.gem 18 Hz)                                       5.32 (m, H.sub.eq -7 W.sub.H =10 Hz)                                          6.62 (s, H-11)                                                                13.24 (s, OH-6)                                                               7.7-8.5 (m, 4 aromatic protons)                               ______________________________________                                    

EXAMPLE X Preparation of 4-demethoxy-6-deoxydaunorubicin and7,9-diepi-4-demethoxy-6-deoxydaunorubicin.

To a solution of 0.065 g of racemic 4-demethoxy-6-deoxydaunomycinone(II: R₁ ═OH, R₂ ═H), prepared as described in Example VIII, in 45 ml ofanhydrous dichloromethane, there were added 1 g of molecular sieve (4ÅMerck), 0.079 g of2,3,6-trideoxy-3-trifluoroacetamido-4-0-trifluoroacetyl-α-L-lyxopyranosylchloride (III: Y═Cl, R₆ ═CF₃ COO, R₇ ═H), 0.029 ml of sym-collidine and0.057 g of silver trifluoromethanesulphonate dissolved in 2 ml ofanhydrous diethyl ether. After 2 hours at room temperature the reactionmixture was filtered and washed with aqueous 0.1 N hydrochloric acid,water, aqueous saturated sodium bicarbonate solution, and water. Thenthe residue obtained by the evaporation of the solvent was taken up inmethanol and after 30 minutes at room temperature the hydrolysis of theC-4'-0-trifluoroacetyl group was completed. This afforded a mixture ofthe diastereoisomers N-trifluoroacetyl-4-demethoxy-6-deoxydaunorubicinand 7,9-diepi-N-trifluoroacetyl-4-demethoxy-6-deoxydaunorubicin: TLC onkieselgel plates (Merck F₂₅₄) using the solvent systemchloroform:acetone (4:1 by volume): Rf 0.16 and 0.13.

The pure diastereoisomers are obtained by chromatographic separation ona column of silica gel using, as eluent, the solvent systemchloroform:acetone (6:1 by volume).

The hydrolysis of the N-protecting group was performed by dissolving theN-trifluoroacetyl derivative in aqueous 0.1 N sodium hydroxide. After 30minutes at 0° C. the solution was adjusted to pH 8 and extracted withchloroform. Evaporation of the solvent to a small volume, followed byaddition of methanolic 0.1 N hydrogen chloride in order to adjust the pHto form 4.5 to 5, afforded 4-demethoxy-6-deoxydaunorubicin and7,9-diepi-4-demethoxy-6-deoxydaunorubicin, as the hydrochlorides. TLC onsilica gel plates (Merck F₂₅₄) using the solvent systemchloroform:methanol:acetic acid:water (80:20:7:3 by volume) Rf 0.26 and0.30.

FD-MS: m/z 482 (MH⁺); 481 (M⁺).

EXAMPLE XI Preparation of 4-demethoxy-4'-epi-6-deoxydaunorubicin and4-demethoxy-4'-epi-7,9-diepi-6-deoxydaunorubicin.

The coupling reaction between racemic 4-demethoxy-6-deoxydaunomycinone(II: R₁ ═OH, R₂ ═H) and2,3,6-trideoxy-3-trifluoroacetamido-4-0-trifluoroacetyl-α-L-arabino-pyranosylchloride (III: Y═Cl, R₆ ═H, R₇ ═CF₃ COO) operating in accordance withthe procedure described in Example X afforded4-demethoxy-4'-epi-6-deoxy-N-trifluoroacetyldaunorubicin and thecorresponding 7,9-diepi derivative. Mild alkaline treatment effectedhydrolysis of the N-trifluoroacetyl group giving4-demethoxy-4'-epi-6-deoxydaunorubicin and4-demethoxy-4'-epi-7,9-diepi-6-deoxydaunorubicin, isolated as thehydrochlorides.

EXAMPLE XII Preparation of 4-demethoxy-4',6-dideoxydaunorubicin and4-demethoxy-4',6-dideoxy-7,9-diepidaunorubicin.

The coupling reaction between racemic 4-demethoxy-6'-deoxydaunomycinone(II: R₁ ═OH, R₂ ═H) and2,3,4,6-tetradeoxy-3-trifluoroacetamido-L-threo-pyranosyl chloride (III:Y═Cl, R₆ ═R₇ ═H) operating in accordance with the procedure described inExample X afforded4-demethoxy-4',6'-dideoxy-N-trifluoroacetyldaunorubicin and thecorresponding 7,9-diepi derivative. Mild alkaline treatment effectedhydrolysis of the N-trifluoroacetyl group giving4-demethoxy-4',6-dideoxydaunorubicin and4-demethoxy-4',6-dideoxy-7,9-diepidaunorubicin isolated as thehydrochlorides.

EXAMPLE XIII Preparation of 4-demethoxy-6-deoxy-doxorubicin

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-6-deoxydaunorubicin prepared accordingto Example X, the title compound was isolated as the hydrochloride.

EXAMPLE XIV Preparation of 4-demethoxy-4'-epi-6-deoxy-doxorubicin.

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-4'-epi-6-deoxydaunorubicin preparedaccording to Example XI, the title compound was isolated as thehydrochloride.

EXAMPLE XV Preparation of 4-demethoxy-4',6-dideoxydoxorubicin.

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-4',6-dideoxydaunorubicin preparedaccording to Example XII, the title compound was isolated as thehydrochloride.

EXAMPLE XVI Preparation of 4-demethoxy-4'-epi-11-deoxydaunorubicin and4-demethoxy-4',7,9-triepi-11-deoxydaunorubicin.

To a solution of 0.7 g of racemic 4-demethoxy-11-deoxy-daunomycinone(II: R₁ ═H, R₂ ═OH), prepared as described in Example IX, in 100 ml ofanhydrous dichloromethane were added 6 g of molecular sieve (4Å Merck),0.785 g of2,3,6-trideoxy-3-trifluoroacetamido-4-0-trifluoroacetyl-α-L-arabinopyranosylchloride (III: Y═Cl, R₆ ═H, R₇ ═CF₃ COO), 0.26 ml of sym-collidine and0.515 g of silver trifluoromethanesulphonate dissolved in 25 ml ofanhydrous diethyl ether. After 20 minutes at room temperature thereaction mixture was filtered and washed with aqueous 0.1 N hydrochloricacid, water, aqueous saturated sodium bicarbonate solution and water.Then the residue obtained by evaporating off the solvent was taken up inmethanol overnight. Evaporation of the methanol afforded a mixture ofthe diastereoisomersN-trifluoroacetyl-4-demethoxy-4'-epi-11-deoxydaunorubicin andN-trifluoroacetyl-4-demethoxy-4',7,9-triepidaunorubicin. TLC onkieselgel plates (Merck F₂₅₄) using the solvent systemchloroform:methanol (4:1 by volume): Rf 0.13 and 0.16, respectively. Thepure diastereoisomers were obtained by chromatographic separation on acolumn of silica gel using, as eluent, the solvent systemchloroform:acetone (97:3 by volume).N-trifluoroacetyl-4-demethoxy-4'-epi-11-deoxydaunorubicin (0.34 g), m.p.208°-210° C., andN-trifluoroacetyl-4-demethoxy-4',7,9-triepi-11-deoxydaunorubicin, m.p.198°-200° C.

3 g of N-trifluoroacetyl-4-demethoxy-4'-epi-11-deoxy-daunorubicin weredissolved in 25 ml of acetone and 25 ml of aqueous 0.2 N sodiumhydroxide. After 30 minutes at room temperature the reaction mixture wasadjusted to pH 3.5 with hydrochloric acid and extracted with chloroformto eliminate impurities. Then the aqueous solution was adjusted to pH 8and extracted with chloroform. The evaporation of the solvent to a smallvolume followed by addition of methanolic hydrogen chloride andprecipitation with diethyl ether afforded4-demethoxy-4'-epi-11-deoxydaunorubicin, as the hydrochloride (0.23 g),m.p. 175°-176° C. TLC on kieselgel plates (Merck F₂₅₄) using the solventsystem chloroform:methanol:acetic acid 40:10:1 by volume): Rf 0.22.

FD-MS m/z 482 (M⁺); 481 (M⁺).

    ______________________________________                                        PMR 60MHz (D.sub.2 O):                                                                      1.35    (d, CH.sub.3 -5'                                                      2.42    (s, CH.sub.3 CO-9)                                                    2.90    (s, CH.sub.2 -10)                                                     3.2-3.6 (m, H-3', H-4'                                                        4.05    (m, H-5')                                                             5.25    (s Broad, H-1' W.sub.H =6 Hz                                          6.96    (s, H-11)                                                             7.76    (s, broad, 4 aromatic protons)                          ______________________________________                                    

The hydrolysis of the N-trifluoroacetyl group of the otherdiastereoisomer operating analogously afforded4-demethoxy-4',7,9-triepi-11-deoxydaunorubicin. TLC on kieselgel plates(Merck F₂₅₄) using the same solvent system Rf 0.24.

EXAMPLE XVII Preparation of 4-demethoxy-11-deoxydaunorubicin and4-demethoxy-7,9-diepi-11deoxydaunorubicin.

The coupling reaction between 0.100 g of racemic4-demethoxy-11-deoxydaunomycinone (II: R₁ ═H, R₂ ═OH) and 0.11 g of2,3,6-trideoxy-3-trifluoroacetamido-4-0-trifluoroacetyl-α-L-lyxopyranosylchloride (III: Y--Cl, R₆ ═CF₃ COO, R₇ ═H) operating in accordance withthe procedure described in Example XVI afforded4-demethoxy-11deoxy-N-trifluoroacetyldaunorubicin, Rf 0.24, and thecorresponding 7,9-diepi derivative. Mild alkaline treatment afforded thehydrolysis of the N-trifluoroacetyl group giving4-demethoxy-11deoxydaunorubicin, as its hydrochloride, m.p. 104°-105°C., TLC Rf 0.17 (chloroform:methanol:acetic acid 40:10:1 by volume),FD-MS: m/z 482 (MH⁺), 481 (M⁺), and4-dememthoxy-7,9-diepi-11-deoxydaunorubicin, as the hydro chloride.

EXAMPLE XVIII Preparation of 4-demethoxy-4',11-dideoxydaunorubicin and4-demethoxy-4',11-dideoxy-7,9diepi-daunorubicin.

The coupling reaction between 0.35 g of racemic4-demethoxy-11-deoxydaunomycinone (11: R₁ ═H, R₂ ═OH) prepared asdescribed in example IX, in 50 ml of anhydrous dichloromethane and 0.245of 2,3,4,6-tetradeoxy-3trifluoroacetamido-L-threopyranosyl chloride(III:Y═Cl, R₆ ═R₇ ═H) operating in accordance with the proceduredescribed in example XVI afforded after chromatographic separation oncolumn of silica gel using as eluent the solvent system toluene-acetone(96:4 v/_(v)), 4-demethoxy-4',11-dideoxy-N-trifluoroacetyldaunorubicin[g 0.170, TLC on kieselgel plates (Merck F₂₅₄) using solvent systemtoluene-acetone (4:1 v/_(v)): Rf 0.53] and4-demethoxy-4',11-dideoxy-7,9-diepi-N-trifluoroacetyldaunorubicin [g0,2, TLC on kieselgel plates (Merck F₂₅₄) using solvent systemtoluene-acetone (4:1 v/_(v)): Rf 0.53] Mild alkaline treatment affordedthe hydrolysis of the N-trifluoroacetyl group giving4-demethoxy-4',11-deoxydaunorubicin, isolated as its hydrochoride, m.p.155°-156°, TLC: Rf 0.40 (chloroform-methanol-acetic acid-water 80:20:7:3by volume).

FD-MS m/z 466 (MH⁺); 465 (M⁺)

EXAMPLE XIX Preparation of 4-demethoxy-11-deoxy-4'-epidoxorubicin.

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-11-deoxy-4'-epidaunorubicin, preparedaccording to Example XVI, the title compound was isolated as thehydrochloride.

EXAMPLE XX Preparation of 4-demethoxy-11-deoxy-doxorubicin.

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-11-deoxy-daunorubicin, preparedaccording to Example XVII, the title compound was isolated as thehydrochloride.

EXAMPLE XXI Preparation of 4-demethoxy-4',11-dideoxydoxorubicin.

Following the process described in U.S. Pat. No. 3,803,124 and using asthe starting material 4-demethoxy-4',11-dideoxy-daunorubicin, preparedaccording to EXAMPLE XVIII, the title compound was isolated as thehydrochloride.

BIOLOGICAL ACTIVITY

The biological activity of the following compound was tested againstHela cells in vitro:

4-demethoxy-4'-epi-11-deoxydaunorubicin

4-demethoxy-11-deoxy-4'-epidoxorubicin

4-demethoxy-11-deoxydaunorubicin

4-demethoxy-6-deoxydaunorubicin

The data in Table 1 show that all of these compounds exert remarkablecytotoxic activity in vitro.

The activity of the compounds 4-demethoxy-4'-epi-11-deoxydaunorubicinand 4-demethoxy-deoxy-daunorubicin was also tested against P388 asciticleukemia in mice. The data in Table 2 show that both of these compoundsexert antitumor activity.

                  TABLE 1                                                         ______________________________________                                        Effect on Hela cells cloning activity.sup.a                                                Dose                   ID.sub.50                                 Compound     (ng/ml)  %             (ng/ml)                                   ______________________________________                                        Daunorubicin 25       21, 42, 50, 8, 16,                                                                          15                                                     12.5     65, 83, 80, 77, 79                                                   6.2      86, 150, 104, 93, 101,                                               3.1      104, 115                                                4-demethoxy-4'-epi-                                                                        100      13,10         40                                        11-deoxy-daunorubi-                                                                        25       56, 82                                                  cin          6.2      60, 105                                                              1.5      78, 109                                                 4-demethoxy-11-                                                                            100      0             25                                        deoxydaunorubicin                                                                          25       50                                                                   6.2      112                                                     4-demethoxy-11-deoxy-                                                                      400      0             20                                        4'-epidoxorubicin                                                                          100      1                                                                    25       33                                                                   6.2      100                                                     4-demethoxy- 250      0             17                                        6-deoxydaunorubi-                                                                          50       4                                                       cin          10       73                                                                   5        119                                                     ______________________________________                                         .sup.a Treatment for 24 hours                                            

                  TABLE 2                                                         ______________________________________                                        Effect against P388 leukemia.sup.a                                                         Dose.sup.b                                                                             T/C.sup.c      Toxic.sup.e                              Compound     (ng/kg)  %        LTS.sup.d                                                                           deaths                                   ______________________________________                                        Daunorubicin 2.9      180      0/10  0/10                                                  4.4      185      0/10  0/10                                                  6.6      190      0/10  3/10                                     4-demethoxy- 6.6      160      0/10  0/10                                     4'-epi-11-deoxy-                                                                           10       160      0/10  0/10                                     daunorubicin 15       160      0/10  0/10                                     4-demethoxy- 4.4      155      0/10  0/10                                     deoxy-daunorubi-                                                                           6.6      120      0/10  7/10                                     cin          10        90      0/10  8/10                                     ______________________________________                                         .sup.a BDFl mice were injected ip with 10.sup.6 leukemia cells.               .sup.b Treatment ip on day 1 after tumor inoculum.                            .sup.c Median survival time of treated mice/median survival time of           controls × 100.                                                         .sup.d Long term survivors.                                                   .sup.e Toxic deaths, evaluated on the basis of zooptic findings.         

What we claim is:
 1. A process for preparing a racemic aglycone, saidprocess comprising reacting 1,2,3,6-tetrahydrophthalic anhydride with analcohol of the formula ROH wherein R is lower alkyl, substituted loweralkyl or aryl to form the monoester of the formula (2): ##STR31##wherein R is as defined above, subjecting the monoester (2) to aFriedel-Crafts reaction with acetyl chloride, followed by mild alkalinetreatment, to give the corresponding α,β unsaturated ketone (3):##STR32## catalytically reducing (3) to form the corresponding4-acetylperhydrophthalate (4) ##STR33## reacting (4) with1,4-dimethoxynaphthalene in the presence of trifluoroacetic anhydrideand trifluoroacetic acid to form a mixture of two isomeric compounds offormula (6) ##STR34## submitting said mixture of isomers (6) to acatalytic reduction of the benzylic carbonyl function, followed bytreatment thereof with sulphuric acid at room temperature, to afford amixture of the tetracyclic isomers of formula (7): ##STR35## treatingthe mixture (7) with sulphuric acid at 80° C. for one hour to give 1:1mixture of the racemic anthracyclinones (8) and (9): ##STR36## treatingsaid mixture first with boiling acetic anhydride in the presence ofp-toluene-sulphonic acid and then with m-chloroperbenzoic acid at roomtemperature for 2 hours to form a diastereomeric mixture of racemic(±)4-demethoxy-6,7-dideoxydaunomycinone and racemic(±)4-demethoxy-7,11-dideoxydaunomycinone, separating said diastereomericmixture by chromatography on silica gel and treating each separatelyobtained racemic compound, separately, with ethylene glycol, inrefluxing benzene and in the presence of p-toluene-sulphonic acid toobtain the corresponding 13 ketals, subjecting the 13-ketals to abenzylic bromination, by treatment with bromine in carbon tetrachloridein the presence of 2,2'-azo-bis-isobutyronitrile, followed by hydrolysisof the ketal group by means of an aqueous solution of hydrogen chloridein acetone, at room temperature for three hours to obtain, separately,the racemic (±)4-demethoxy-6-deoxy-daunomycinone and racemic(±)4-demethoxy-11-deoxydaunomycinone. 2.Monomethyl-4-acetyl-perhydrophthalate.
 3. (±)4-demethoxy-6-deoxydaunomycinone.